The invention relates to the art of electric arc welding and more particularly to a small portable electric arc welder with an integrated, internal battery charger.
In recent years, a secondary marketing strategy by leading manufacturers of electric arc welders has been to sell a large number of small portable electric arc welders used domestically and in small job shops. This expansion of welding capabilities to individuals has greatly increased the arc welding field and has created a situation where many small facilities include capabilities for electric arc welding. Such tremendous increase in the number of electric arc welders being used by individuals has created a demand to enhance the capabilities of these small portable welders so the welders can be used for diverse applications between the occasional use of the welder to actually weld. So far, the ability to diversify the capabilities of portable electric arc welders has not been accomplished, except to provide an auxiliary power outlet. The present invention is an effort to expand the use of a portable electric arc welder.
The present invention is an improvement in a portable electric arc welder having an internal power source that creates a DC voltage between two output terminals. A portable electric welder is a small welder of the type that is carried about a shop or garage and has a weight of less than about 100 pounds and is rated at less than about 300 amperes. Indeed, most of the portable electric arc welders, such as the SP series manufactured by The Lincoln Electric Company and sold by the thousands at retail outlets, has a rating of less than 200 amperes. This type of portable electric arc welder sold in retail outlets to individuals is modified to have an integral, internal battery charger. This integrated, internal battery charger is used to charge batteries, such as a 12 volt vehicle battery, using the power source of the welder. In accordance with the invention, the portable electric arc welder appears to be the same and has the same general size as an existing light duty welder. However, the welder is used between occasional welding operations to charge an automobile battery. In accordance with another aspect of the invention, the electric arc welder is also provided with an integral device for rotating an automobile starter. This can be standard terminals of a battery charger or a motor starting device connected to the existing battery of a motor vehicle. In this later situation, a bypass circuit is provided so that when an automobile needs emergency starting, due to a low battery, the welder is capable of being connected to the starting device while bypassing the existing vehicle battery. The main aspect of the present invention is providing an integral battery charger. A secondary aspect of the invention, which mayor may not be incorporated into the portable welder, is the motor starting device driven by the same power source as the welder and the battery charger. Consequently, the standard portable, light duty electric arc welder of the present invention has the capability of charging batteries and, in one implementation, the capability of replacing the existing battery as a means of supplying a high level of DC current. The two added capabilities of the welder are used for lead acid type batteries, such as batteries having a voltage capability of at least about 12 volts DC. These two capabilities are included in a constant voltage type arc welding power supply, which may or may not include a wire feeder as an integral component. This new small portable welder includes a switch to select the welding mode or the battery charging mode. If the third capability is included then the switch includes a battery eliminator mode, i.e. a mode for starting an automobile. The welder has standard positive and negative welding power leads for a gun and cable and a workpiece. The integral starting device includes a separate pair of terminals connected to the terminals of the power source of the welder.
In the welding mode, the welder will operate as a conventional constant voltage arc welder. The internal power source will include the normal electrode and workpiece welding cables. In cases where the wire feeder is an integral part of the power source, the electrode cable will be part of the welding gun and torch. Furthermore, when in the welding mode, the other modes of operation may or may not be electrically turned off or inactive. In the battery charger or battery eliminator modes, a separate pair of terminals, designated positive and negative, are provided for connection to the battery studs. These terminals may be part of the battery charger or separate for connection into the wiring system of a vehicle. Furthermore, in the battery charging mode, a standard 12 volt battery or group of batteries may be charged. Of course, batteries of higher voltage may also be charged by changing the internal charging circuit. The charge voltage is internally selected. In the battery eliminator mode or starting mode, the power source acts like a battery and provides the current needed to start or power various apparatuses, such as the starting motor of a motor vehicle. In one modification when employing this mode of operation of the portable electric arc welder, an additional cable is used. This cable is connected to a specifically designed adaptor or housing permanently attached to the battery. This starting device allows the operation of a starting motor in a motor vehicle by passing current to a starting motor, but not to the battery. This prevents the portable arc welder from adversely affecting the battery when the welder is used to start an internal combustion engine.
In accordance with an aspect of the invention, a standard portable electric arc welder having a power source creating a DC voltage between two output terminals and welding output leads for performing a welding operation is improved by an internal battery charger integrated with the welder. The battery charger utilizes standard battery charging technology and has an input stage connected to the terminals of the power source and output leads connectable to a battery. The battery charger includes a standard charging sequence circuit operable by an input enabling signal. The voltage from the welder to charge the battery in accordance with standard technology is a constant voltage identified by the battery charge. A manual selector switch on the welder is movable between a first position connecting the terminals of the power source to the welding output leads and a second position creating the battery charging input enabling signal. In accordance with another aspect of the invention, a welding gun or torch, with a weld trigger, is connected to one of the output leads and a circuit is provided for operating the power source when both the trigger is closed and the selector switch is in the first position activating the welding mode.
In accordance with another aspect of the invention, the selector switch has a third position to activate an integral actuating device to start a motor vehicle. This device is from the battery charger or is attached to at least one of the output terminals of the power source by a connector. In this case, a circuit is used to close the connector when the selector switch is in the third position. Consequently, when the automobile battery is low, the welder is connected to the starting device to direct starting current to a bypass circuit or through the battery charger to the winding system of the vehicle.
In accordance with another aspect of the invention, a spark inhibitor is provided when the battery operating modes of the welder are used. A large resistor has parallel switch. The switch is closed only when current flow through the resistor is sensed. Thus, if a spark condition exists, the switch will be open and the large resistor is placed in series with the power lead. Another ancillary aspect of the invention is provision of a polarity switch on the output side of the battery operating devices. This polarity switch allows the welding device connected to the output of the portable welder to be manually adjusted between an electrode positive or an electrode negative mode of operation.
The primary object of the present invention is the provision of a small, portable electric arc welder with an integrated, internal battery charger using the same power source for either welding or battery charging.
A further object of the present invention is the provision of a small electric arc welder which has dual capabilities and can be sold to individuals at retail outlets. These and other objects and advantages will become apparent taken together with the accompanying drawings.